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SubjectRE: [PATCH v3 7/9] KVM: x86: Implement Intel Processor Trace MSRs read/write
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> >>> +		case MSR_IA32_RTIT_ADDR0_A ... MSR_IA32_RTIT_ADDR3_B: {
> >>> + u32 eax, ebx, ecx, edx;
> >>> +
> >>> + cpuid_count(0x14, 1, &eax, &ebx, &ecx, &edx);
> >>
> >> Please cache the cpuid_count result, or do the cpuid_count after testing
> >> vmx_pt_supported() (which you can use instead of going through kvm_x86_ops).
> >
> > Hi Paolo,
> > Thanks for your reply. I have cache EAX in "struct pt_desc" and will initialize in vmx_vcpu_setup().
> > +struct pt_desc {
> > + unsigned int addr_num;
> > + struct pt_ctx host;
> > + struct pt_ctx guest;
> > +};
> > But kvm_init_msr_list() is invoked too early, I have to read from hardware. So, what about change like this.
> >
> > - cpuid_count(0x14, 1, &eax, &ebx, &ecx, &edx);
> > - if (!kvm_x86_ops->pt_supported() || msrs_to_save[i] -
> > - MSR_IA32_RTIT_ADDR0_A >= (eax & 0x7))
> > + if (!kvm_x86_ops->pt_supported())
> > continue;
> > + cpuid_count(0x14, 1, &eax, &ebx, &ecx, &edx);
> > + if (msrs_to_save[i] -
> > + MSR_IA32_RTIT_ADDR0_A >= (eax & 0x7))
> > + continue;
>
> For kvm_init_msr_list it's okay. But can you please add a
> pt_msr_count() function?
>

Of course, I will fix in next version. Thanks!

Luwei Kang

> >>
> >>> + if (!kvm_x86_ops->pt_supported() || msrs_to_save[i] -
> >>> + MSR_IA32_RTIT_ADDR0_A >= (eax & 0x7))
> >>> + continue;
> >>> + break;
> >

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